Hydrocaffeic acid and esters as antioxidants



March v16, 1948,

l.. w. ELDER Er Al.

HYDROCAFFEIG ACID AND lESIERS AS ANTIOXIDANTS Filed Ja. 29, 1945 Patented. Mar. 16, 1.948

S PATENT OFFICE nYDRooAFFETc Aem AND Esrnns As IOXIDANT Lucius w. Elder, Madison, and nai-old s. Levenson, Orange, Nr.1.,

of Delaware assigner-s to General Foods Corporation, New York, N. Y.,

a corporation l Application January 29, 1945, Serial No. 575,132

12 Claims. (Cl. 26o-398.5)

This invention relates tothe preservation or stabilization of animal and vegetable fats and oils, and of products containing the same, against deleterious oxidative changes.

It is well known that animal and vegetable oils and fats often undergo oxidative deterioration upon st: ding in contact with air which leads to the -levelopment of undesirable tastes and odors,` a-, for example, those commonly associated with rancidity. In the case of food products containing edible oils and fats, for example,

` such deterioration often renders the product unt for human consumption, This deterioration is attributed to the fact that some of the constituents of these fats and oils possess a tendency peroxides and thus halt the production of the tion period elapses before there is an apprecia ble absorption of oxygen 'by the oil or fat, and the eectiveness of an antioxidant can be measured in terms of its ability to prolong the induc-V tion period. This measurement can be carried out conveniently with a Barcroft-Warburg apparatus in comparison with a control, the effectiveness of the antioxidant being generallyexpressed numerically as a protection factor which is the ratio of the induction periodfor the stabilized oil or fat to that for the control, i. e., the untreated oil or fat.

The following data, were obtained by the aforementioned method and apparatus, the fats and oils being mechanically shaken in an atmosphere of oxygen, and the citrus oils being maintained various final oxidation products or at least retard it until the oils and fats can be utilized.

In accordance with the invention, the deterioration of animal and vegetable fats and oils is prevented or at least greatly retarded by the incorporation therein of small amounts of hydrocaffeic acid or certain esters thereof. Hydrocaffeic acid is the saturated derivative of caiieic acid which results from the addition of two atoms of hydrogen to the double bond of the side chain.

Various polyhydroxy phenols have been found in the past to have antioxygenic activity, the ortho and para polyhydroxy compounds such as hydroquinone and catechol being more effective than the corresponding meta compounds such as resorcinol. Caffeic acid, which is a derivative of the former type, is also known to have antioxygenic activity of a high order,` and it has been thought that this activity is due in part to the presence in the side chain of the unsaturated double bond between the catechol nucleus and the carboxyl group. It now appears that this l is not the case and that the activity of caffeic acid is due primarily to its hydroxy grouping. On the contrary, we have discovered that hydrocaffeic acid, in which the side chain is saturated, is much more effective thancafeic acid, being from one and a `half to three times as eiective in substrates such as lard, cod liver oil, peanut oil, oilve oil, and citrus oils.

'Ihis greater effectiveness of hydrocaifeic acid is illustrated by the following comparison with eaffeic acid. When an oxidizable oil or fat is exposed to oxygen or air under standardized conditions, a definite time interval termed the inducat C. while the rest were maintained at 90 C.

Table I Antioxidant (0.02 g./1oo m1.)

' (gonrtigtli H dr ff i o y cca e c Substrate oidlzmlt) Caec Amd Acid mi I P r P ins? P. F. 3 hrs? P. F.

Corn Oil 17. 4 29. 1. 70 29. 6 1. 70 shortening 3 108 174 1. 61 193 1. 79 Wheat Germ Oil 9. 0 15. 6 l. 70 17. 5 1. 90 Cottonseed Oil 17. 1 30. B l. 80 35. 3 06 0. 62 (l. 70 1. 13 2. 18 3. 52 28. 8 78. 8 2. 74 114. 3 3. 97 Butter Oil..." 30.6 188 6. 15 318 10. 4 Refined Cocoa But- 1 Induction Period. 2 Protection Factor. l A commercial hydrogenated shortening known as "XXXVream.

A comparison of P. F. values shows the most pronounced superiority of hydrocaffeic acid over caieic acid with cod liver oil and lard, and a less marked but still large superiority with the citrus oils, olive oil, butter oil, peanut oil, and rened cocoa butter.

The protection factors in the other four cases do not show such striking improvement, in accordance with common experience that most antioxidants do not give high protection factors in vegetable oils, but the absolute differences in I. P. values are also to be considered and the increase of 19 hrs. effected with the hydrogenated shortening, for example, is of considerable practical significance.

In addition to the greater effectiveness of hydrocaifeic acid as illustrated by the above data, oxygenic activity. in particular. the esters of hythere is a qualitative diiference in the solubility drocaifeic acid` with alkyl alcohols (monohydric of caileic and hydrocaileic acids in fats and oils saturated aliphatic alcohols, which may be which is of great practical advantage. This adstraight or branched-chain primary, secondary, vantage is illustrated by Table II, which shows n or tertiary alcohols). 'I'he following Table III the increasing antioxidant protection ail'orded illustrates the eifectiveness of some of these esby increasing amounts of caiieic and hydrocafters, namely, esters of hydrocailfeic acid with norfeic acids in lard at 90 C. mal primary alcohols ranging from one to twelve ,Table H y carbon atoms, in lard at 90 C. Also shown in l Table III is the comparative eifectiveness aiIorded by the corresponding esters of caieic acid under Antioxidant H dr s i two right-hand columns for equimolar concen- Substrate. Lard Concentration, Caiieic Acid y Ai c trations of the different esters are calculated on W100 ml' 15 the assumption that the protection factors for the 1 E, P F 1 p., P F esters of the two acids vary with concentration in hrs. hrs. the same manner as those for the acids. Cogitroi, No Antioxidant Table I .38%. P. F. Calculated for 01 Antioxidant in Lard At Equlmolar Concen- '02'x" Concentration of 0.02 trations Corres- '0.41"' v g./l00 ml. pending to 0.02 g. I2- IIIIIIIIIII Acid/100ml- Ester l Approximate concentration for saturated call'eic acid solution at 25 Caffete Hydrocafeate 90 C. Gamme Hydroi Approximate concentration for saturated hydrocaeic acid solu- P F f-igt tion at Q0 C. I. P., P F. I. P., P F

i Induction period for control==2.25. hrs. hrs. 'I'he greater quantity of hydrocaieic acid that como] No 1 can be dissolved in the lard (0.04%) provides atde- AAtogidant. ogg() n? 21%,, im gree of protection almost four times as grea as c1 1 l M 1 .e 24.6 135.2 37.6 26.0 ses that obtainable with the maximum concentra- @my A2 2U 119.8 33.3 24.0 am tion of caieic acid (0.02%). The same is qualitaa 101.4 1 29.0 gg: 36.5 tively true with other fats and oils. Thus the f6 14:1 "5,33" 23.8 "gj superiority of hydrocafleic acid over caifelc acid Averages 24 5 38 2 at the same concentration, as demonstrated by Table I, is enhanced in view of the greater amount l V l e for the acids from Table II. that can be dissolved in the fat or oil. Moreover, i @nlmhuo hrs.

where dispersed or undissolved antioxidant is not i Excluding the Values for the acidsobjectionable and the amounts used are increased 4o It will be seen from the above figures that on a beyond the saturation values. the superiority of molar basis, there is a remarkable uniformity in hydrocaieic acid is not only maintained but inthe protection factors for caieic acid and for its creased as illustrated at the concentration of 0.2 estersI indicating that the antioxidant effect of g./100 ml. These relationships are illustrated by these compounds is due primarily to the 3,4 hythe curves in the drawing. droxyl groups. A similar uniformity is observed Hydrocaleic acid can be used for the stabilizawith esters of hydrocaifeic acid, but at a, higher tion of fatty substances and oils of both animal level of effectiveness than is obtained with caieic and vegetable origin which are subject to oxidiaacid and its esters. This increased effectiveness tive deterioration upon standing inV Contact with is attributed to the different manner in which the air, as well as food products and other mate- 5" saturated and unsaturated side chains affect the rials containing them. Among these fatty subreactivity of the catechol nucleus as stated above. stances and oils may be mentioned by way of ex- In the case of hydrocarleic acid per se, however, it ample fatty acids and fatty acid Soaps, glyceride is evidentv that some other effect is obtained in fats and oils, the terpene-containing essential oils. view of the sharp increase in effectiveness of this etc. Lard in particular is an example of an animal acid as compared with its esters, and it is believed fat which tends to turn rancid. Vegetable fats that in hydrocail'eic acid with its saturated side and oils such as cottonseed oil, coconut oil, corn chain, there is a synergistic action between the oil, lwheat germ oil, soy bean oil, peanut oil, redihydroxy grouping and the carboxyl group which ned cocoa butter, olive oil, orange oil. lemon oil, is absent in caieic acid where the side chain is etc., may be treated with hydrocaifeic -acid and unsaturated. their keeping qualities improved, particularly The above theoretical considerations are oered since such vegetable fats and oils are often subas the best available explanation of the eilectivejected to refining operations which remove some ness of hydrocaffeic acid and its esters, and alnaturally occurring antioxidants. Shortenings of though the chemistry involved in the use of these the dry plastic type comprising partially hydro- 55 antioxidants is not fully understood, this explanagenated rened vegetable oils, and similar shorttion is believed to be correct. Whatever the true enings produced by compounding an oil with a explanation may be, however, tests such as those hard fat, may likewise be stabilized by the inset forth above demonstrate that hydrocaeic vention. Hydrocaieic acid is also well suited for acid and its esters do possess antioxygenic activuse in food products containing such fatty subity of ahigh order.

stances and oils such as bakery products, oil- The antioxidants of the present invention can bearing nuts and fruits, fruit juices, etc. be added to or mixed with the fat `or oil in any 'I'he invention is not restricted to the use of hysuitable or known manner. The amount to be drocaifeic acid per se but includes also the use used is not critical, but in general only a very of certain derivatives which exhibit similar antismall amount of the order of a small fraction of the same conditions. The values shown in the f a percent will be al1 that is needed. On the other hand, there is no reasonable minimum which will not yield some result. Hence it will be understood that the invention is not restricted to the details of the foregoing description, and that reference should be had to the appended claims for a deinition of its limits.

What is claimed is:

1. A process of stabilizing fats, fatty acids, fatty acid derivatives and oils of animal and vegetable origin against oxidative deterioration which comprises adding thereto a material selected from the group consistingof hydrocaffeic acid and alkyl esters thereof. t

2. A process of stabilizing glyceride fats and oils against oxidative deterioration which comprises adding thereto a material selected from the group consisting of hydrocaifeic acid and alkyl esters thereof.

3. A process of stabilizing essential oils againstV oxidative deterioration which comprises adding thereto a material selected from the group consistlng of hydrocaffeic acid and alkyl esters thereof.

4. A process of stabilizing fats, fatty acids, fatty acid derivatives and oils of animal and vegetable origin against oxidative deterioration which comprises adding hydrocaifeic acid thereto.

5. A process of stabilizing glyceride fats and oils against oxidative deterioration which comprises adding hydocaffeic acid thereto.

6. A process of stabilizing essential oils against oxidative deterioration which comprises adding hydrocaffeic acid thereto.

7. A composition of matter stabilized against oxidative deterioration and containing a material of the group consisting of fats, fatty acids, fatty acid derivatives and oils of animal and vegetable origin and a member of the group consisting of hydrocaifeic acid and alkyl esters thereof.

8. A composition .of matter stabilized against oxidative deterioration and containing a glyceride oil or fat and a member of the group consisting of hydrocaffeic acid and alkyl esters thereof.

9. A composition of matter stabilized against oxidative deterioration and containing an essential oil and a member of the group consisting of hydrocaieic acid and alkyl esters thereof.

10. A composition of matter stabilized against oxidative deterioration and containing a material of the group consisting of fats. fatty acids. fatty acid derivatives and oils of animal and vegetable origin and hydrocaieic acid.

11. A composition of matter stabilized against oxidative deterioration and containing a glyceride oil or fat and hydrocaieic acid.

.12. A composition of matter stabilized against oxidative deterioration and containing an essential oil and hydrocafieic acid.

LUCIUS W. ELDER. HAROLD S. LEVENSON.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENT Name Date Mattill et al Nov. 9, 1943 Number 

